This invention relates to rotary cutting cylinders and a method of making rotary cutting cylinders.
In the past, rotary cutting cylinders have been made by forming a cylinder such as on a lathe. A longitudinal slot is then made in the cylinder to receive a cutting rule. Several tangential notches are then milled into the cylinder, adjacent the slot. The notches are spaced along the length of the slot. The notches are carefully milled so that the bases of the notches form flat faces parallel to the walls of the slot. A threaded hole is made through the face at the base of each notch, into the slot. Set screws are then threaded into the holes, into the slot, to engage the cutting rule and secure the rule in the slot.
Several different forming steps are required to make rotary cutting cylinders according to this prior method. Thus, the prior method is both time consuming and expensive, and requires expensive equipment and skilled labor. The resulting rotary cutting cylinders have thus been expensive.
The inventors has made a new rotary cutting cylinder and a method of making rotary cutting cylinders that reduces the number of forming steps, shortens the manufacturing time, and requires less equipment and less labor than the prior methods of making such cylinders. The resultant cutting cylinder is of simple construction and is less expensive than the prior cutting cylinders.
According to the inventor's method, a cylinder is formed, such as on a lathe. During this forming step, a number of longitudinally spaced grooves are formed in the cylinder. These grooves preferably extend circumferentially around the cylinder so that they can be formed with the lathe. However, partial grooves, tangential cuts, or notches can be made instead. Then, a longitudinal slot is formed in the cylinder, crossing the grooves. This slot is wide enough to receive a cutting rule, a stiffening shim, and a mounting bar. The mounting bar is a rectangular cross-section bar with set screws spaced at regular intervals. This mounting bar is a stock item that can be trimmed to fit the slot. The grooves in the cylinder are spaced complementary to the set screws so that a tool can be inserted in the groove to tighten and loosen the set screws. When the set screws are tightened, they push the cutting rule and mounting bar against the opposite walls of the slot, frictionally engaging the cutting rule and mounting bar in the slot.
The rotary cutting cylinder is thus formed in two steps, eliminating the step of milling notches and the step of forming threaded holes for set screws. This reduces the amount of labor required to form the cylinder. The resulting rotary cutting cylinder is of simple and reliable construction.